Most manufacturing facilities rely upon conveyor systems to transport articles through the facility. Finished products are normally loaded into cartons of appropriate size and transported to a storage area for later processing, or moved directly to the docking area for immediate transport. It can be appreciated that different products are normally stored in different sections of the storage area for ease of retrieval, and/or need to be transported to different sections of the docking area depending on the particular delivery site destination.
Accordingly, many industrial conveyor systems include sortation lines in which articles are carried along on a primary or main line endless belt conveyor and are diverted to secondary or takeaway conveyors depending on the desired destination within the facility. Various diverter assemblies have been used in the past to accomplish this task.
Early devices included piston-actuated pushers that deflect an article to a takeaway conveyor oriented at approximately 90.degree. from the main line conveyor. In order to ensure that the next succeeding article on the main line conveyor is not hindered by the pusher and/or there is no interference with the diverted article, the minimum required gap between articles for this type of diverter design is relatively large. Alternatively, the main line conveyor is operated in stepped fashion, stopping briefly to allow the article transfer to take place. In both instances, overall operation is relatively slow, inefficient and costly.
In order to improve efficiency, diverter assemblies have been developed incorporating wheels that are angularly skewed from the longitudinal orientation of the main line conveyor. This allows the diverted article to be positively and quickly carried in a lateral direction off the main line conveyor towards a takeaway conveyor. One of the most successful of these prior art diverter concepts involves a diverter assembly including a plurality of wheel assemblies, each assembly having a wheel coupled to a central hub. The wheels swivel between an aligned, straight-through orientation relative to main line conveyor travel and a skewed, divert orientation, providing straight-through conveyance and diversion, respectively. The wheels are situated so as to extend slightly above the level of the main line conveyor. The rows of wheels are actuated simultaneously by a controller. This diverter wheel assembly design is generally disclosed in U.S. Pat. No. 4,372,435 to Bradbury, assigned to the present assignee.
A further example of such an assembly is disclosed in U.S. Pat. No. 3,983,988 to Maxted et al. In one embodiment (similar to that of the assignee's as described above), the diverter assembly includes diverter wheels that are maintained at substantially the same elevational height (i.e. slightly above the level of the main line conveyor) and pivoted between an aligned, straight-through orientation when transporting to a position further downstream and a skewed position when diverting is desired. The system includes a plurality of rows of wheels, the wheels in the second and each succeeding row being skewed at a greater angle than the next preceding row.
The '988 patent discloses a second embodiment wherein the diverter wheels in each of the plurality of rows are permanently maintained in a skewed position, again with the second and succeeding rows being skewed at a greater angle. The wheels are positioned inoperatively below the level of the main line conveyor to allow straight-through, downstream conveyance. The wheels of the assembly are raised above the level of the main line conveyor to provide the diverting function.
Each of these operative designs presents certain drawbacks. With the latter, pop-up design having permanently skewed wheels, it can be appreciated that the wheels in the non-diverting position must be below the level of the main line conveyor. Accordingly, positive contact with the conveyed article is interrupted or lessened to a degree as it passes over the diverter assembly. In certain situations, this can disrupt the constant speed of the conveyed articles along the main line conveyor, progressively altering the gap distance between successive articles. With the former, pivotable wheel design having a constant elevation above the main line conveyor, it can be appreciated that when the article contacts the wheels in the aligned orientation relative to straight-through conveyor travel, the article has a tendency to bounce or bobble as it passes over the diverter assembly. This also disrupts consistent advance resulting in progressively changing gap distance between successive articles.
Thus, it is necessary to correct the tendency of each of the previously discussed prior art diverter assembly designs that tends to randomly alter the gap distance between successive articles. This prior tendency adversely effects the efficient operation of the main line conveyor since the spacing between articles becomes erratic, making it more difficult to control the article handling equipment at the end of the line.
In an effort to avoid these drawbacks, recent developments in diverter assemblies have incorporated a combination of the wheel pivoting and elevating action. More particularly, the diverter assembly is designed so that the pivoting of the diverter wheels is directly integrated with the elevating of the wheels above the main line conveyor. An example of such a diverter assembly is disclosed in U.S. Pat. No. 4,598,815 to Adama. The Adama diverter assembly includes diverter wheels that generally are level with the main line conveyor belt and rest in an aligned, straight-through orientation. When diversion of an article is desired, the diverter wheels are simultaneously raised and pivoted within the diverter assembly. The diverter wheels thus engage the articles and lift them slightly, both removing part of the forward momentum and positively redirecting the orientation of the articles toward the side. The diverter wheels in effect turn the articles toward the takeaway conveyor.
The Adama diverter assembly has other drawbacks. More particularly, the lift mechanism and pivot mechanism are integrated. This integration decreases the ability to precisely control the individual pivoting and elevating functions. The integration of the functions also increases the opportunity for operational breakdown of the entire assembly. Additionally, integration of the pivot and lift mechanisms reduces the flexibility for adjustment to optimize the divert operation, for example, for particular size articles, particular weight articles and boxes or cartons of different materials.
A need therefore exists for a diverter assembly that provides independent pivoting and elevating of diverter wheels to allow maximum efficiency, flexibility and control of the divert operation. Such an assembly should provide positive, level contact for non-diverted articles to efficiently maintain article straight-through conveyance, and smooth operation through the entire processing stream. It is now proposed that maintenance of a constant and minimum gap distance between successive articles is necessary to allow the main line conveyor to be operated at a more controlled speed, while still maintaining maximum conveying efficiency. Of course, the generally slower, controlled speed operation of a conveyor system provides gentler article handling and requires less energy, and hence is more efficient. With the reduced gap between articles, the same or even increased through-put of the system can be obtained.